Common side-blotched lizard

Uta stansburiana

The common side-blotched lizard is a species of side-blotched lizard found on the Pacific Coast of North America. It is notable for having a unique form of polymorphism wherein each of the three different male morphs utilizes a different strategy in acquiring mates. The three morphs compete against each other following a pattern of rock, paper, scissors, where one morph has advantages over another but is outcompeted by the third.

The specific epithet ''stansburiana'' is in honor of Captain Howard Stansbury of the US Corps of Topographical Engineers, who collected the first specimens while leading the 1849-1851 expedition to explore and survey the Great Salt Lake of Utah.

Appearance

The common side-blotched lizard is a species of small iguanid lizard. Males can grow up to 60 mm from snout to vent, while females are typically a little smaller. The degree of pigmentation varies with sex and population. Some males can have blue flecks spread over their backs and tails, and their sides may be yellow or orange, while others may be unpatterned. Females may have stripes along their backs/sides, or again may be relatively drab. Both sexes have a prominent blotch on their sides, just behind their front limbs. Coloration is especially important in common side-blotched lizards, as it is closely related to the mating behavior of both males and females.

Reproduction

Female side-blotched lizards lay clutches with an average of 5.1 eggs and a maximum of 9 eggs in a single clutch. Smaller clutch sizes, often associated with yellow-throated females, have an increased frequency of eggs bursting upon being laid or egg binding, suggesting an upper physiological limit to how much a female can invest in each individual egg she lays.

Food

Side-blotched lizards display feeding behavior which can be influenced by sex or season. In a study conducted by Best ''et al''., these lizards were found to consume diets largely based upon arthropod populations within the area, within a given season. These populations vary by year, and different arthropod populations will fluctuate seasonally. The study showed a correlation between sex and diet, giving way to a number of theories that speculate why gender has an effect on feeding behavior and diet. One mechanism proposes the behavior differences depend on gender, such as guarding territories and attracting mates, are responsible for, or a contributing factor in, feeding behavior. Alternatively, the sexual difference in feeding behavior could also act in favor of reducing intraspecific competition for resources, with individuals eating prey appropriate for their respective size .